Conventional Customer Premises Equipment (CPE) devices, including desktop telephones, mobile and portable telephones, facsimile machines, Personal Digital Assistants (PDA's) and computers and related electronic devices such as video cassette recorders, televisions, remote controls, calculators and the like, present all information entry keys for all functions. Such keys are generally adapted for use in cooperation with a single visual display -- regardless of whether the functions are relevant in the current context of the communication. Moreover, such visual displays which are generally liquid crystal displays (LCD's) do not present sufficient information to prevent users from entering an irrelevant or improper key. As a result, an erroneous key selection results in either an error message or similar indication that an invalid key has been entered -- neither of which is desirable from a user standpoint.
In an effort by system designers to implement additional functions, conventional keyboards have further incorporated additional keys which again correspond to functions which are neither relevant nor operable in all communication contexts. As a result, the size as well as the complexity of such keyboards has been correspondingly increased. While efforts have been made to reduce this inherent complexity, these efforts have heretofore proven unsuccessful.
In the mobile telephone communications industry, for example, efforts have been made to minimize the number of entry keys while increasing the number of available features. Such efforts have involved the incorporation of entry keys which may be used to initiate multiple functions. In other applications, such as calculators and other electronic devices, as well as the aforementioned mobile telephones, &lt;shift&gt; keys have also been utilized. These multi-function entry keys have been designed to provide specific functions which are tied to particular communication contexts. This correspondence, however, is still neither readily apparent nor logically referenced. For example, many wireless communications devices, and in particular cellular telephones, i.e. wireless telephones operable in the microwave band between approximately 1.8 GHZ and 2.2 GHZ, utilize an entry key labeled &lt;SEND&gt; for use in both answering an incoming call as well as to originate an outgoing call. Similarly, many vehicular cellular telephones utilize a &lt;CONTROL&gt; button or entry key which may be used to store selected telephone numbers, lock the hand-set, adjust the volume of the received communication and initiate other selected operations.
Consider, for example, the conventional vehicular mobile telephone handset shown in FIG. 1 and designated generally by reference numeral 10. As shown, mobile telephone hand-set 10 includes a first class of fixed-label entry keys 12 disposed on the keypad for generating Dual-Tone Multi-Frequency (DTMF) signals (i.e. digits 0-9 plus the star and pound). Hand-set 10 further includes a single visual display 14 which, as referenced above, does not present detailed information sufficient to advise users from entering an irrelevant or incorrect key. Finally, hand-set 10 includes a second class of fixed label action keys 16, i.e. &lt;STO&gt;, &lt;REC&gt;, &lt;SEND&gt;, etc., for initiating selected functions. As further referenced above, the &lt;SEND&gt; key 18 is ambiguously operative for answering both incoming calls and for originating an outgoing call. A &lt;CONTROL&gt; key 20 operative to initiate a plurality of other functions such as locking the hand-set, increasing the volume, storing a desired telephone number and performing other selected operations is also provided. Vehicular mobile telephone hand-sets of this type provide ambiguous and imprecise functionality, are complicated to use and, as a result, are highly prone to user error.
As a further example, consider the prior art hand portable mobile telephone which is shown in FIG. 2 and designated generally by reference numeral 22. Portable telephone 22 is known to those skilled in the art as the NEC Model T300 portable phone. Like the prior art vehicular mobile telephone of FIG. 1, portable phone 22 includes a first class of fixed-label entry keys 24 for generating DTMF signals. Hand-set 22 further includes a second class of fixed-label action keys 26, i.e., &lt;SEND&gt;, &lt;STO&gt;, &lt;RCL&gt;, &lt;FCN&gt;, &lt;CLR&gt;, &lt;END&gt;, and &lt;PWR&gt; for initiating selected functions. Significantly, each of the fixed-label entry keys 24 and 26 are tied to a single visual display 28.
The most notable problem encountered in the operation of the above interactive electronic devices is that the required syntax is neither apparent nor consistent. In conventional mobile telephones, for example, storing a telephone number requires a three-step process, i.e. initiation of a store sequence, identification of a telephone number sought to be stored, and selection of a storage location. Similar steps are also required when storing interim calculations or numeric sequences on conventional calculators, remote controls, VCRs, etc.. These steps and their store sequences vary widely from manufacturer to manufacturer and from device to device. Yet, in most cases, little if any "on-line" or "during operation" help -- other than an error message -- is provided to guide the user through the required syntax.
In a further effort to minimize the number of entry keys while increasing the number of available features, interface designers and, in particular, the assignee of the present invention, U.S. West Advanced Technologies, Inc., has contemplated the incorporation of dynamic visual display screens in mobile and desktop telephones and related electronic devices. These "dynamic" visual display screens are designed to present to the user a plurality of context sensitive function labels. In operation, these function labels are adapted to be accessed by depressing one or more soft-label signaling keys which are provided in electrical communication with the dynamic visual display. See, for example, copending U.S. patent application Ser. No. 08/089,146 which is commonly owned by the assignee of the present invention.
As those skilled in the art will recognize, while the use of soft-label signaling keys presents a major advance over the prior art, this approach is nonetheless still limited in flexibility due to the inherent design requirement that items must be in specific places. In addition, the user is provided no direct manipulation or sensory feedback. In operation, the user must physically depress a button to access the corresponding desired function label, which subsequent testing has proven is less intuitive than direct manipulation of the label itself.
As the number of consumer electronic devices increases, interface designers have turned attention towards the employment of touch screens which, in contrast to the above devices, permit users to activate functions or to interact with information using direct manipulation. Such direct manipulation dramatically improves the ease-of-use of the interface, and thus increases the desirability of the device employing the interface. However, in contrast to the benefits derived from a direct manipulation interface via a touch screen, usability is simultaneously inhibited by the touch screen for the following reason. Due to the nature of the touch screen, users are apt to use their fingertips to activate/select items from the touch screen. Fingertips, however, are inexact pointing devices and thus generally unsuitable for such touch screens which require precise location of the finger press. Thus, the likelihood of activating the wrong function or selecting the wrong data is increased by the ambiguity of selections with the fingertip. This ambiguity actually inhibits the device's usability and thus its desirability.
Consequently, a need has therefore developed to provide an improved touch screen user interface which may be implemented in interactive electronic devices of the type referenced above. More specifically, a need has developed to provide such an improved interface wherein the function labels may be directly manipulated. Such an interface should also provide disambiguation means to guide the user to the appropriate function label while, at the same time, preventing the user from accessing an incorrect key.